1. Field of the Invention
A personal stair lift to transport an individual up and down a stairway on a chair supported on a rail mounted rack.
2. Description of the Prior Art
As the population ages the need to improve mobility continues to increase. These needs range from personal mobility vehicles to personal stair lifts. Personal stair lifts provide motorized systems to transport individuals up and down stairways on a seat supported rail mounted rack.
The following patent documents are representative of the prior art relating to personal stair lifts.
U.S. Pat. No. 2,212,388 describes an elevator for use with stairs comprising rail means arranged to support a car and means for supporting the rail means. The supporting means comprises a plurality of clamp means engaging the rail means arranged that the inclination of the rail means is adjustable to correspond to the slope of the stairs.
U.S. Pat. No. 2,888,099 shows a chair lift comprising a rail assembly mounted in a stairway including a load rail and a leveling rail, a carriage mounted upon the rail assembly, a main shaft journalled in the carriage and a seat supporting frame pivotally mounted upon the main shaft. Resilient driving rollers are mounted upon the main shaft in engagement with the load rail. A motor is mounted upon the carriage in driving relationship with the resilient rollers. Leveling rollers are mounted upon the frame in engagement with the leveling rail.
U.S. Pat. No. 4,915,573 shows a stair lift comprising a pair of power jacks linked to a stair or step associated with a vehicle such as a trailer adjacent the vehicle doorway. The jacks operate in tandem to raise or lower the stair or step with a person standing thereon.
U.S. Pat. No. 5,217,089 relates to a motor driven stair lift device operable along the track to move a carrier along the track
U.S. Pat. No. 5,992,935 shows a stair lift with a swivel chair comprising a seat pivotally connected to a support having a mechanical activating means for swiveling the seat around the first axis of rotation.
U.S. Pat. No. 7,131,522 teaches a stairs lift system capable of converting stairs climbing operation into a walking movement along a horizontal plane. The system comprises an existing substrate, flight of stairs, and a second, overlying layer of stairs. Each one of the overlying stairs comprises a lifting element. Mechanical, electronic or hydraulic means are provided for lifting the lifting element up to the height of next-in-line overlaying stair. The lifting means are activated when sensing the presence of a subject having stepped on the first-in-line lifting element. The first-in-line lifting element returns to the initial position once the subject has stepped over to the next-in-line stair; and so forth.
U.S. Pat. No. 7,140,475 teaches a motor brake coupled to the rotatable motor drive shaft. The brake includes a shaft-mountable support that rotates uniformly with the drive shaft. One or more brake shoes, which can include flyweights or the like, are hingedly mounted to the support and include brake pads. A centripetal force is applied to the brake shoes using one or more springs or other biasing means that bias the brake pads against a braking surface when rotation of the shaft is below a minimum rotational velocity. The brake pads disengage from the braking surface when shaft rotation exceeds the minimum rotational velocity. The centrifugal force induced and applied to the brake shoes and brake pads by rotation of the motor drive shaft overcomes the biasing force to disengage the brake pads from the braking surface, which may be the housing of a motor to which the brake is affixed. U.S. Pat. No. 7,156,208 shows a stair lift comprising a lift assembly driven along a rail including a chassis supporting a load bearing member such as a seat. The chassis is formed by a main member on which are mounted a drive assembly and a leveling assembly for maintaining the seat horizontal by altering the orientation of the chassis with respect to the rail as the lift assembly moves along the rail. One or both of the drive and leveling assemblies may be pivotally mounted on the chassis to permit rotation about a vertical axis so as to accommodate bends in the rail.
U.S. Pat. No. 7,225,899 relates to a stair lift for lifting and lowering a person on a rail on a stairway comprising a carriage mountable to the rail having a track engaging drive, and a motor to power the drive, the powered drive causing the carriage to move along the rail. There is a central support post mounted on the carriage and an offset arm connected to the seat support post. The offset arm is mounted to the carriage in one of a left side or a right side position. A seat is mounted on the offset arm. A notched late secures the seat in position on the offset arm in either the left side or right side position and permits the seat to swivel between a sideways facing position and an upward facing position to facilitate the person getting into and out of the seat.
U.S. Pat. No. 7,600,611 describes a stairlift comprising a rail combination with a carriage and footrest which allows the footrest to be positioned below the level of the first step.
US 2008/0203775 relates to a stairlift chair in which the seat and armrests move simultaneously when the chair is folded. In a preferred embodiment the footrest also folds, with the armrests and seat, when the chair is folded.
Other patent documents include U.S. Pat. Nos. 4,174,023; 7,568,555; JP 2127383 (A) and JP 2005213011 (A).